Shrinkage Template

An additional dimensional stability evaluation was done with a shrinkage template apparatus (Figure 1.2). 

Characterization of the samples by TGA and CHN analysis shows that the template was effectively removed (C < 0.2 wt%). Small-angle X-ray scattering data of the calcined solid shows a reduction in the unit cell due to thermal shrinkage, while the values for the Fenton samples coincide with the starting precursor. Our approach therefore completely preserves the unit cell corresponding to the diameter of the micelles contained in the mesophase. 

More recently, ionic liquids have also been used as additives. Lee and coworkers explain that ionic liquids may ad as a template during the sol-gel process redudng the shrinkage of the matrix by pore filling and behave as a stabilizer to proted Candida rugosa lipases [184]. 

Preparation of MCM-41 materials [1] usually includes a high temperature calcination step that in fact opens mesopores by removing structure directing molecules (template) as well as results in the structure shrinkage due to high temperature condensation of silanol groups [2], Functionalization of mesoporous materials with organosilanes is often employed to synthesize materials of desired surface properties for advanced adsorption and catalytic applications [3] as well as to improve their stability [4]. 

A rich variety of materials (including precursors) have been incorporated into the template-directed synthesis.33 169 170 Curable liquid prepolymers are particularly attractive because they have been widely used in replica molding with resolutions better than a few nanometers. By judicially selecting a monomer, the volume shrinkage involved in... 

Monodispersed 35 nm colloidal silica spheres were used to template a periodic mesoporous polymer [71]. Divinylbenzene was used to make a cross-linked rigid polymer replica, ethylene glycol dimethacrylate ensured that it was flexible and shrinkable, while mixtures of the two were used to vary the degree of shrinkage. In addition, the mesoporous polymer replicas were themselves... 

Films are typically allowed to dry immediately after deposition to drive the silica condensation reaction toward completion. However, the film may not be fully condensed and stable after drying, and postsynthesis treatments are often employed to improve film stability, reduce shrinkage upon template removal, and drive the condensation reaction toward completion. 

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